Field
The present disclosure relates to a recording element board used to discharge liquid such as ink, and to a liquid discharge head having the recording element board.
Description of the Related Art
An example of a method by which a liquid discharge head, e.g., an inkjet recording head, discharges liquid, is the thermal inkjet system where the liquid is heated to cause film boiling, and force of bubbling is used. A liquid discharge head used in the thermal inkjet system has a recording element board on which are formed a discharge orifice that discharges liquid, a pressure chamber communicating with the discharge orifice, a channel that supplies liquid to the pressure chamber, and a supply port that supplies liquid to the channel. A heating resistance element (heater) is formed within the pressure chamber of the recording element board, with liquid being discharged from the discharge orifice by discharge energy that the heating resistance element has generated.
When liquid is discharged by such as liquid discharge head, the discharged liquid has a column-like shape, including a main droplet and a slender droplet tail that follows the main droplet, extending therefrom. This droplet tail often becomes separated from the main droplet in flight, due to the difference in speed between the leading end and trailing end of the liquid column, and becomes minute liquid droplets called satellites. Satellites landing at positions on the recording medium deviated from the main droplet can cause deterioration of image quality.
A known method of reducing occurrence of such satellites to cause the bubble, generated by application of thermal energy from the heating resistance element to separate liquid within the pressure chamber from liquid in the channel, to communicate with the atmosphere at the time of discharging. Using this method makes it easier for portions that can become satellites to be separated from the main droplet before exiting the discharge orifice, since the rear portion of the discharged liquid has a speed component heading toward the heating resistance element, so liquid that becomes satellites outside of the discharge orifice and flies can be reduced.
Further, International Publication No. 2010/044775 discloses art in which dimensions, such as the height of the pressure chamber, the size of the discharge orifices, and so forth, are adjusted so that the more liquid is included in the main droplet as compared to the droplet tail, thereby reducing satellites. In the art described in International Publication No. 2010/044775, the heating resistance element is larger in size than the opening of the discharge orifice.
However, the timing of the bubble communicating with the atmosphere may be late in the art described in International Publication No. 2010/044775. Accordingly, there still have been cases where the rear portion of the droplet becomes separated from the main droplet portion, and satellites occur.